An inverted wheel type moving body is typically controlled to travel in such a manner that the position of the center of mass of the body is constantly corrected to maintain the stable state by driving right and left driving wheels. By mounting a transportation object such as a person or an inanimate object on the moving body, transportation can be made in a simple way. In such a moving body, sudden stop or sudden acceleration may cause overturn of the moving body. A moving body equipped with sub wheels in order to prevent such an overturn during the travelling is disclosed (patent document 1).
For example, according to a vehicle in the patent document 1, sub wheels are arranged in a front-back direction of drive wheels. The sub wheels are provided in end parts of struts extended and retracted by actuators. An inclination is detected by a detector that detects a moment. According to the inclination that is detected, the strut is deployed by the actuator to bring the sub wheel contact with the ground.
[Patent Document 1] Published Japanese Translation of PCT International Publication for Patent Application, No. 2000-514680